Documentation
¶
Index ¶
- func ObjectName(v interface{}) string
- type CommandBus
- type CommandEventMarshaler
- type CommandHandler
- type CommandProcessor
- type CommandsSubscriberConstructor
- type DuplicateCommandHandlerError
- type EventBus
- type EventHandler
- type EventProcessor
- type EventsSubscriberConstructor
- type Facade
- type FacadeConfig
- type JSONMarshaler
- type NoProtoMessageError
- type NonPointerError
- type ProtobufMarshaler
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func ObjectName ¶
func ObjectName(v interface{}) string
ObjectName name returns object name in format [package].[type name]. It ignores if the value is a pointer or not.
Types ¶
type CommandBus ¶
type CommandBus struct {
// contains filtered or unexported fields
}
CommandBus transports commands to command handlers.
func NewCommandBus ¶
func NewCommandBus( publisher message.Publisher, generateTopic func(commandName string) string, marshaler CommandEventMarshaler, ) (*CommandBus, error)
type CommandEventMarshaler ¶
type CommandEventMarshaler interface {
// Marshal marshals Command or Event to Watermill's message.
Marshal(v interface{}) (*message.Message, error)
// Unmarshal unmarshals watermill's message to v Command or Event.
Unmarshal(msg *message.Message, v interface{}) (err error)
// Name returns the name of Command or Event.
// Name is used to determine, that received command or event is event which we want to handle.
Name(v interface{}) string
// NameFromMessage return the name of Command or Event from Watermill's message (generated by Marshal).
//
// When we have Commnad or Event marshaled to Watermill's message,
// we should use NameFromMessage instead of Name to avoid unnecessary unmarshaling.
NameFromMessage(msg *message.Message) string
}
CommandEventMarshaler marshals Commands and Events to Watermill's messages and vice versa. Payload of the command needs to be marshaled to []bytes.
type CommandHandler ¶
type CommandHandler interface {
// HandlerName is the name used in message.Router while creating handler.
//
// It will be also passed to CommandsSubscriberConstructor.
// May be useful, for example, to create a consumer group per each handler.
//
// WARNING: If HandlerName was changed and is used for generating consumer groups,
// it may result with **reconsuming all messages**!
HandlerName() string
NewCommand() interface{}
Handle(ctx context.Context, cmd interface{}) error
}
CommandHandler receives a command defined by NewCommand and handles it with the Handle method. If using DDD, CommandHandler may modify and persist the aggregate.
In contrast to EvenHandler, every Command must have only one CommandHandler.
type CommandProcessor ¶
type CommandProcessor struct {
// contains filtered or unexported fields
}
CommandProcessor determines which CommandHandler should handle the command received from the command bus.
func NewCommandProcessor ¶
func NewCommandProcessor( handlers []CommandHandler, generateTopic func(commandName string) string, subscriberConstructor CommandsSubscriberConstructor, marshaler CommandEventMarshaler, logger watermill.LoggerAdapter, ) (*CommandProcessor, error)
func (CommandProcessor) AddHandlersToRouter ¶
func (p CommandProcessor) AddHandlersToRouter(r *message.Router) error
func (CommandProcessor) Handlers ¶
func (p CommandProcessor) Handlers() []CommandHandler
type CommandsSubscriberConstructor ¶ added in v0.4.0
type CommandsSubscriberConstructor func(handlerName string) (message.Subscriber, error)
CommandsSubscriberConstructor creates subscriber for CommandHandler. It allows you to create a separate customized Subscriber for every command handler.
type DuplicateCommandHandlerError ¶ added in v0.4.0
type DuplicateCommandHandlerError struct {
CommandName string
}
func (DuplicateCommandHandlerError) Error ¶ added in v0.4.0
func (d DuplicateCommandHandlerError) Error() string
type EventBus ¶
type EventBus struct {
// contains filtered or unexported fields
}
EventBus transports events to event handlers.
func NewEventBus ¶
type EventHandler ¶
type EventHandler interface {
// HandlerName is the name used in message.Router while creating handler.
//
// It will be also passed to EventsSubscriberConstructor.
// May be useful, for example, to create a consumer group per each handler.
//
// WARNING: If HandlerName was changed and is used for generating consumer groups,
// it may result with **reconsuming all messages** !!!
HandlerName() string
NewEvent() interface{}
Handle(ctx context.Context, event interface{}) error
}
EventHandler receives events defined by NewEvent and handles them with its Handle method. If using DDD, CommandHandler may modify and persist the aggregate. It can also invoke a process manager, a saga or just build a read model.
In contrast to CommandHandler, every Event can have multiple EventHandlers.
type EventProcessor ¶
type EventProcessor struct {
// contains filtered or unexported fields
}
EventProcessor determines which EventHandler should handle event received from event bus.
func NewEventProcessor ¶
func NewEventProcessor( handlers []EventHandler, generateTopic func(eventName string) string, subscriberConstructor EventsSubscriberConstructor, marshaler CommandEventMarshaler, logger watermill.LoggerAdapter, ) (*EventProcessor, error)
func (EventProcessor) AddHandlersToRouter ¶
func (p EventProcessor) AddHandlersToRouter(r *message.Router) error
func (EventProcessor) Handlers ¶
func (p EventProcessor) Handlers() []EventHandler
type EventsSubscriberConstructor ¶ added in v0.4.0
type EventsSubscriberConstructor func(handlerName string) (message.Subscriber, error)
EventsSubscriberConstructor creates a subscriber for EventHandler. It allows you to create separated customized Subscriber for every command handler.
type Facade ¶
type Facade struct {
// contains filtered or unexported fields
}
Facade is a facade for creating the Command and Event buses and processors. It was created to avoid boilerplate, when using CQRS in the standard way. You can also create buses and processors manually, drawing inspiration from how it's done in NewFacade.
func NewFacade ¶
func NewFacade(config FacadeConfig) (*Facade, error)
func (Facade) CommandBus ¶
func (f Facade) CommandBus() *CommandBus
func (Facade) CommandEventMarshaler ¶
func (f Facade) CommandEventMarshaler() CommandEventMarshaler
type FacadeConfig ¶
type FacadeConfig struct {
// GenerateCommandsTopic generates topic name based on the command name.
// Command name is generated by CommandEventMarshaler's Name method.
//
// It allows you to use topic per command or one topic for every command. [todo - add to doc]
GenerateCommandsTopic func(commandName string) string
// CommandHandlers return command handlers which should be executed.
CommandHandlers func(commandBus *CommandBus, eventBus *EventBus) []CommandHandler
// CommandsPublisher is Publisher used to publish commands.
CommandsPublisher message.Publisher
// CommandsSubscriberConstructor is constructor for subscribers which will subscribe for messages.
// It will be called for every command handler.
// It allows you to create separated customized Subscriber for every command handler.
CommandsSubscriberConstructor CommandsSubscriberConstructor
// GenerateEventsTopic generates topic name based on the event name.
// Event name is generated by CommandEventMarshaler's Name method.
//
// It allows you to use topic per command or one topic for every command. [todo - add to doc]
GenerateEventsTopic func(eventName string) string
// EventHandlers return event handlers which should be executed.
EventHandlers func(commandBus *CommandBus, eventBus *EventBus) []EventHandler
// EventsPublisher is Publisher used to publish commands.
EventsPublisher message.Publisher
// EventsSubscriberConstructor is constructor for subscribers which will subscribe for messages.
// It will be called for every event handler.
// It allows you to create separated customized Subscriber for every event handler.
EventsSubscriberConstructor EventsSubscriberConstructor
// Router is a Watermill router, which will be used to handle events and commands.
// Router handlers will be automatically generated by AddHandlersToRouter of Command and Event handlers.
Router *message.Router
CommandEventMarshaler CommandEventMarshaler
Logger watermill.LoggerAdapter
}
func (FacadeConfig) CommandsEnabled ¶
func (c FacadeConfig) CommandsEnabled() bool
func (FacadeConfig) EventsEnabled ¶
func (c FacadeConfig) EventsEnabled() bool
func (FacadeConfig) Validate ¶
func (c FacadeConfig) Validate() error
type JSONMarshaler ¶
type JSONMarshaler struct {
NewUUID func() string
}
func (JSONMarshaler) Marshal ¶
func (m JSONMarshaler) Marshal(v interface{}) (*message.Message, error)
func (JSONMarshaler) Name ¶
func (m JSONMarshaler) Name(cmdOrEvent interface{}) string
func (JSONMarshaler) NameFromMessage ¶
func (m JSONMarshaler) NameFromMessage(msg *message.Message) string
type NoProtoMessageError ¶
type NoProtoMessageError struct {
// contains filtered or unexported fields
}
func (NoProtoMessageError) Error ¶
func (e NoProtoMessageError) Error() string
type NonPointerError ¶
func (NonPointerError) Error ¶
func (e NonPointerError) Error() string
type ProtobufMarshaler ¶
type ProtobufMarshaler struct {
NewUUID func() string
}
func (ProtobufMarshaler) Marshal ¶
func (m ProtobufMarshaler) Marshal(v interface{}) (*message.Message, error)
func (ProtobufMarshaler) Name ¶
func (m ProtobufMarshaler) Name(cmdOrEvent interface{}) string
func (ProtobufMarshaler) NameFromMessage ¶
func (m ProtobufMarshaler) NameFromMessage(msg *message.Message) string
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